The polymerization and copolymerization of .alpha.-olefins, and acetylenic monomers with so-called Ziegler-Natta catalysts, which are generally defined as a mixture of a group I-III metal alkyl and a transition metal complex from group III-VIII, are well established in the chemical industry. However, catalyst improvements would be of great practical importance if better control over molecular weight and molecular weight distribution could be obtained, the use of undesired excess of co-catalysts were eliminated, and stereoregular polymers could be easily prepared.
As such, there is a need to control stereochemistry in a great many chemicals and polymers and chiral metal catalysts offer an efficient means to do this. The design of a chiral metal catalyst necessarily relies on the design of appropriate ligands which create an asymmetric environment about the metal center. Certain classes of organolanthanide catalysts which are highly active for a variety of reactive purposes are known and described in U.S. Pat. Nos. 4,668,773 and 4,801,666. Organolanthanide hydrides, (Cp'.sub.2 LnH).sub.2 and (Me.sub.2 SiCp".sub.2 LnH).sub.2, (Cp'=N.sub.5 (CH.sub.3).sub.5 C.sub.5, Cp"=N.sub.5 (CH.sub.3).sub.4 C.sub.5 are known to effectively and selectively catalyze a number of olefin transformations including hydrogenation, oligomerization/polymerization, and hydroamination. Heretofore it has not been known whether an appropriate coordination environment could be devised to effect metal-centered asymmetric catalytic transformation and to obtain favorable characteristics, such as extremely rapid kinetics, large turnover capacity, and reactivity tunable with the specific chiral ligand used. The synthesis of stereoregular polymers has been reported with the use of chiral organo-group IV (Ti, Zr, Hf) catalysts having approximate C.sub.2 symmetry. Such catalysts resulted in isospecific polymerization of .alpha.-olefins. Most of the ligands for these "C.sub.2 " catalysts are based upon indenyl or related cyclopentadienyl components, and are difficult and expensive to synthesize. In only a few cases are the isotacticities of the polymeric products at a useful level.